Fluid-pumping system employing air-driven pump and employing at least one pulsation dampener

ABSTRACT

In a fluid-pumping system comprising a pump and a pulsation dampener, which is arranged to dampen pressure pulsations, the pump is driven by air delivered at a regulated pressure. The pulsation dampener is arranged to be charged via an associated regulator, which is arranged to regulate the charging air pressure by reference to the air pressure in an averaging tank. Preferably, the pulsation dampener comprises two apertured walls, between which a diaphragm is mounted, one such wall being mounted so as to limit displacement of the diaphragm toward the air-side chamber and the other wall mounted so as to limit displacement of the diaphragm toward the fluid-side chamber. Two similar dampeners may be employed, one to dampen pressure surges and the other to dampen pressure drops.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of U.S. Provisional PatentApplication Serial No. 60/353,709, which was filed on Jan. 31, 2002, andthe disclosure of which is incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

This invention pertains to a fluid-pumping system employing anair-driven pump, which may be a double-diaphragm pump, and employing atleast one pulsation dampener to dampen pressure pulsations at an outletof the air-driven pump.

BACKGROUND OF THE INVENTION

In fluid-pumping systems, pressure pulsations are known to occur influids being pumped. It is known to employ pulsation dampeners to dampensuch fluctuations. Such pulsations are known to occur even if air-drivenpumps are employed, whether single-diaphragm pumps, double-diaphragmpumps, or piston pumps.

One example of a pulsation dampener is disclosed in U.S. Pat. No.4,979,441. The pulsation dampener disclosed therein employs an inner,perforated tube, an outer, rigid tube, and an intermediate, elastomericsleeve. Gas pressure in a space between the outer, rigid tube and theintermediate, elastomeric sleeve dampens pressure pulsations in a fluidbeing pumped through the inner, perforated tube. With the pulsationdampener disclosed therein, it is difficult to compensate for minutelosses of gas pressure in the space between the outer, rigid tube andthe intermediate, elastomeric sleeve.

SUMMARY OF THE INVENTION

This invention provides a fluid-pumping system comprising a pump havingan inlet and an outlet and a pulsation dampener arranged to dampenpressure pulsations at the outlet. The pump is arranged to be driven byair delivered to the pump at a regulated pressure. The pulsationdampener is arranged to be charged by air delivered at a regulatedpressure via a pressure-reducing regulator, which is arranged toregulate the air pressure in the charging line by reference to theaverage pressure of the air driving the pump.

Preferably, the pressure-reducing regulator is arranged to regulate theair pressure in the charging line to a selected differential above orbelow the average pressure of the air driving the pump. In a preferredembodiment, wherein an averaging tank is connected to a driving line,via an orifice, the pressure-reducing regulator is arranged to regulatethe air pressure in the charging line by reference to the air pressurein the averaging tank. The fluid-pumping system may comprise twopulsation dampeners, i.e., one arranged to dampen pressure drops at theoutlet and another arranged to dampen pressure surges at the outlet.

Preferably, each pulsation dampener comprises an air-side chamber, whichis adapted to be charged through the charging line, a fluid-sidechamber, which is adapted to communicate with the outlet conduit so thatthe fluid pumped through the outlet conduit can enter the fluid-sidechamber, and an elastomeric diaphragm, which is mounted so as toseparate the outer and fluid-side chambers. Preferably, each pulsationdampener comprises two apertured walls, between which the diaphragm ismounted. One said wall is mounted so as to limit displacement of thediaphragm in a direction to decrease the volume of the air-side chamberand, thereby, to increase the volume of the fluid-side chamber. Theother wall is mounted so as to limit displacement of the diaphragm in adirection to increase the volume of the air-side chamber and, thereby,to decrease the volume of the fluid-side chamber. Preferably, outsidesaid one wall, the air-side chamber has a volume at least three timeslarger than the volume between the apertured walls.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partly schematic layout of a fluid-pumping system employingan air-driven pump, employing a pulsation dampener, and embodying thisinvention.

FIG. 2, on a larger scale, is a partly cross-sectioned, partlybroken-away view of the pulsation dampener and of adjacent portions ofan outlet conduit, in the system of FIG. 1.

FIG. 3, on an intermediate scale, is a layout of two pulsation dampenersand adjacent portions of an outlet line, in a modified system embodyingthis invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

As illustrated in FIG. 1, a fluid-pumping system 10 comprises anair-driven pump 20, which may be a double-diaphragm pump, which isarranged to draw a fluid through an inlet conduit 22, into an inlet 24of the pump 20, and which is arranged to pump the fluid from an outlet26 of the pump 20, through an outlet conduit 28. The pump 20 is drivenby air delivered to the pump 20 through a driving line 32, via apressure-reducing regulator 30, which receives air at a higher pressurefrom a source (not shown) and which reduces the air pressure to aregulated pressure suitable for driving the pump 20.

Moreover, the system 10 comprises a pulsation dampener 40, which isarranged to dampen pulsations in the pressure of the fluid being pumpedthrough the outlet conduit 28. The pulsation dampener 40 is charged byair delivered to the pulsation dampener 40, through a charging line 42,via a pressure-reducing regulator 50, which receives air at a higherpressure from the same source and which reduces the air pressure in thecharging line 42 to a regulated pressure by reference to the averagepressure of the air driving the pump 20.

As illustrated in FIG. 1, an averaging tank 60 is connected to thedriving line 32, via an orifice 62, and the pressure-reducing regulator50 is arranged to regulate the air pressure in the charging line 42 byreference to the air pressure in the averaging tank 60. Alternatively,the average pressure of the air driving the pump 20 may beelectronically measured via a pressure transmitter (not shown) which isconnected to the driving line 32 and which is arranged to averagemultiple pressure readings and to control the pressure-reducingregulator 50 accordingly.

As illustrated in FIG. 2, the pulsation dampener 40 comprises anair-side chamber 72, which has a variable volume and which is chargedthrough the charging line 42, a fluid-side chamber 74, which has avariable volume and which communicates with the outlet 26 of the pump20, via the outlet conduit 28, so that the fluid pumped through theoutlet 26 of the pump 20 can enter the fluid-side chamber 74, and anelastomeric diaphragm 80, which is mounted so as to separate theair-side chamber 72 and the fluid-side chamber 74. The pulsationdampener 40 comprises two apertured walls, between which the diaphragm80 is mounted. One said wall 82 is mounted so as to limit displacementof the diaphragm 80 in a direction to decrease the volume of theair-side chamber 72 and, thereby, to increase the volume of thefluid-side chamber 74. The other wall 84 is mounted so as to limitdisplacement of the diaphragm 80 in a direction to increase the volumeof the air-side chamber 74 and, thereby, to decrease the volume of thefluid-side chamber 74. Moreover, outside the apertured wall 82, theair-side chamber 72 has a volume at least three times larger than thevolume between the apertured walls 82, 84.

If the pressure of the fluid entering the fluid-side chamber 74 from theoutlet conduit 28 surges above the pressure of the air in the air-sidechamber 72, the diaphragm 80 is displaced so as to decrease the volumeof the air-side chamber 72 and so as to increase the volume of thefluid-side chamber 74, whereby to dampen the pressure surge in the fluidbeing pumped through the outlet conduit 28. If the pressure of the fluidentering the fluid-side chamber 74 from the outlet conduit 28 dropsbelow the pressure of the air in the air-side chamber 72, the diaphragm80 is displaced so as to increase the volume of the air-side chamber 72and so as to decrease the volume of the fluid-side chamber 74, wherebyto dampen the pressure drop in the fluid being pumped through the outletconduit 28. Depending upon whether the air pressure in the air-sidechamber 72 is regulated to a normal pressure above, below, orapproximately at the normal pressure of the fluid in the fluid-sidechamber 74, via the pressure-reducing regulator 50, the pulsationdampener 40 can be thus controlled so as to dampen pressure surges inthe fluid being pumped through the outlet conduit 28, so as to dampenpressure drops therein, or so as to dampen pressure surges therein andpressure drops therein.

Because of the low mass of the diaphragm 80 and the large volume of airin the air-side chamber 72, the pulsation dampener 40 responds quicklyto pressure fluctuations in the fluid being pumped through the outletconduit 28. Moreover, even if minute losses of air in the air-sidechamber 72 occur, the pressure-reducing regulator 50 compensates forthose losses so as to maintain the air pressure in the air-side chamber72.

If the fluid being pumped by the system 10 is a liquid or employs aliquid carrier, the pulsation dampener 40 may be advantageously providedwith a liquid sensor 90, which is mounted in the air-side chamber 72,which is arranged to detect any liquid that may have entered theair-side chamber 72, and which is arranged, if the sensor 90 detects anyliquid, to activate an alarm signal, shut down the system 10, or both.

As illustrated in FIG. 3, two pulsation dampeners 40A, 40B, are employedin a modified system 10A, each being similar to the pulsation dampener40, each being controlled similarly, and each communicating similarlywith the outlet 26 of the pump 20, via the outlet conduit 28. Thepulsation dampener regulator 40A can be thus controlled so as to dampenpressure surges in the fluid being pumped through the outlet conduit 28.The pulsation dampener 40B can be thus controlled so as to dampenpressure drops in the fluid being pumped through the outlet conduit 28.

What is claimed is:
 1. A fluid-pumping system comprising a pump havingan inlet and an outlet and a pulsation dampener arranged to dampenpressure pulsations at the outlet, wherein the pump is arranged to bedriven by air delivered at a regulated pressure via a pressure-reducingregulator associated with the pump, wherein the fluid-pumping systemfurther comprises means for averaging the pressure of the air drivingthe pump wherein the pulsation dampener is arranged to be charged by airdelivered to the pulsation dampener through a charging line, at aregulated pressure, via a pressure-reducing regulator associated withthe pulsation dampener, and wherein the pressure-reducing regulatorassociated with the pulsation dampener is arranged to regulate thepressure of the air charging the pulsation dampener by reference to theaverage pressure of the air driving the pump.
 2. The fluid-pumpingsystem of claim 1 wherein the pressure-reducing regulator associatedwith the pulsation dampener is arranged to regulate the air pressure inthe charging line to a selected differential above or below the averagepressure of the air driving the pump.
 3. A fluid-pumping systemcomprising a pump having an inlet and an outlet and a pulsation dampenerarranged to dampen pressure pulsations at the outlet, wherein the pumpis arranged to be driven by air delivered to the pump through a drivingline, which is charged with air at a regulated pressure via apressure-reducing regulator associated with the pump, wherein anaveraging tank is connected to the driving line via an orifice, whereinthe pulsation dampener is arranged to be charged by air delivered to thepulsation dampener, at a regulated pressure, via a pressure-reducingregulator associated with the pulsation dampener, and wherein thepressure-reducing regulator associated with the pulsation dampener isarranged to regulate the air pressure in the charging line by referenceto the air pressure in the averaging tank.
 4. The fluid-pumping systemof claim 3 wherein the pressure reducing regulator associated with thepulsation dampener is arranged to regulate the air pressure in thecharging line to a selected differential above or below the air pressurein the averaging tank.
 5. The fluid-pumping system of claim 1, 2, 3, or4 wherein the pulsation dampener comprises an air-side chamber, which isadapted to be charged through the charging line, a fluid-side chamber,which is adapted to communicate with the outlet so that the fluid pumpedthrough the outlet can enter the fluid-side chamber, and an elastomericdiaphragm, which is mounted so as to separate the air-side andfluid-side chambers.
 6. The system of claim 5 wherein the pulsationdampener comprises two apertured walls, between which a diaphragm ismounted, wherein one said wall is mounted so as to limit displacement ofthe diaphragm in a direction to decrease the volume of the air-sidechamber and, thereby, to increase the volume of the fluid-side chamber,and wherein the other wall is mounted so as to limit displacement of thediaphragm in a direction to increase the volume of the air-side chamberand, thereby, to decrease the volume of the fluid-side chamber.
 7. Afluid-pumping system comprising a pump having an inlet and an outlet, apulsation dampener arranged to dampen pressure drops at the outlet, anda pulsation dampener arranged to dampen pressure surges at the outlet,wherein the pump is arranged to be driven by air delivered to the pumpthrough a driving line, which is charged with air through a chargingline, at a regulated pressure, via a pressure-reducing regulatorassociated with the pump, and wherein each pulsation dampener isarranged to be charged by air delivered to the pulsation dampenerthrough a charging line at a regulated pressure via an associatedpressure-reducing regulator, which is arranged to regulate the airpressure in the charging line by reference to the average air pressurein the driving line.
 8. The fluid-pumping system of claim 7 wherein thepressure-reducing regulator associated with the pulsation dampeneradapted to dampen pressure drops is arranged to regulate the airpressure in the charging line to a selected differential below theaverage air pressure in the driving line and wherein thepressure-reducing regulator associated with the pulsation dampeneradapted to dampen pressure surges is arranged to regulate the airpressure in the charging line to a selected differential above theaverage air pressure in the driving line.
 9. A fluid-pumping systemcomprising a pump having an inlet and an outlet, a pulsation dampenerarranged to dampen pressure drops at the outlet, and a pulsationdampener arranged to dampen pressure surges at the outlet, wherein thepump is arranged to be driven by air delivered to the pump through adriving line, which is charged with air at a regulated pressure, whereinan averaging tank is connected to the driving line via an orifice, andwherein each pulsation dampener is arranged to be charged by airdelivered to said pulsation dampener through a charging line at aregulated pressure via an associated pressure-reducing regulator, whichis arranged to regulate the air pressure in the charging line byreference to the air pressure in the averaging tank.
 10. Thefluid-pumping system of claim 9 wherein the pressure-reducing regulatorassociated with the pulsation dampener adapted to dampen pressure dropsis arranged to regulate the air pressure in the charging line to aselected differential below the air pressure in the averaging tank andwherein the pressure-reducing regulator associated with the pulsationdampener adapted to dampen pressure surges is arranged to regulate theair pressure in the charging line to a selected differential above theair pressure in the averaging tank.
 11. The fluid-pumping system ofclaim 7, 8, 9, or 10 wherein each pulsation dampener comprises anair-side chamber, which is adapted to be charged through the chargingline, a fluid-side chamber, which is adapted to communicate with theoutlet so that the fluid pumped through the outlet can enter thefluid-side chamber, and an elastomeric diaphragm, which is mounted so asto separate the air-side and fluid-side chambers.
 12. The system ofclaim 11 wherein each pulsation dampener comprises two apertured walls,between which the diaphragm is mounted, one said wall being mounted soas to limit displacement of the diaphragm toward the air-side chamberand the other wall being mounted so as to limit displacement of thediaphragm toward the fluid-side chamber.